WO2001089820A2 - Compositions and methods for coating a substrate - Google Patents

Abstract

Provided are compositions and methods for coating a substrate. In one aspect, the invention features a coated substrate that includes a substrate of interest; a first layer comprising inorganic filler particles dispersed in at least one hydrolyzable silane; and a second layer comprising at least one compatibilizing agent in adhesive contact with the substrate. The invention has a wide spectrum of important applications including providing plastic or synthetic resin substrates with good abrasion resistance.

Description

COMPOSITIONS AND METHODS FOR COATING A SUBSTRATE

CROSS-REFERENCE TO RELATED APPLICATION

The present application is a continuation of U.S. Provisional Application U.S.S.N. 60/206,592 filed on May 23, 2000 and entitled "Compositions and Methods for Coating Substrates". The application is also a continuation of U.S. Pat. Application. No. USSN 09/616,820. The disclosures of the U.S.S.N. 60/206,592 and 09/616,820 applications are incorporated herein by reference.

FIELD OF THE INVENTION

The invention generally relates to compositions and methods for coating a substrate. In one aspect, the invention features coated substrates. Also provided are coating compositions as well as methods for making coated substrates. The invention has many important applications including protecting a wide range of articles from damage.

BACKGROUND OF THE INVENTION

Many polymers have been used as glass substitutes. Polymers and polymer materials (sometimes called substrates) such as plastics generally provide good flexibility as well as favorable weight and impact resistance. In addition, many polymers and polymer materials are easy to process and manipulate.

Many different substrates have been employed in commercial, research, medical, and consumer settings. There is also increasing use of such substrates in construction, recreation, transportation and military applications. See generally Katsemberis, et al, Progress in Organic Coatings, Vol. 34, pp. 130-134, (1998). See also Schmidt, H.K. et al. (1994) MRSSymp. Proc. Vol. 346; Winkler, R.P et al. (1999) Thin Solid Vol. 351; and U.S. Pat. Nos. 5,015,523 and 6,008,285.

Particular attention has focused on using plastic substrates for optical implementations. Of particular interest has been eye or face wear adapted for aerospace, aviation, transportation, military or automotive use. Optical implementations formatted for recreational, consumer, photographic or medical use have also attracted much interest.

There have been efforts to improve the performance characteristics of optical implementations and specifically eye or face wear adapted for safety and/or ophthalmic applications.

As an illustration, many lenses have been made from a synthetic resin called CR39™ (polydiethyleneglycol bisallyl carbonate). Lenses made from this resin have generally provided good abrasion resistance.

However, there has a growing need for optical implementations that are lighter and thinner than CR-39™.

Attempts to address this need have involved use of other substrates. In particular, synthetic resins and high reflective index resins such as bisphenol A polycarbonate have been used. See e.g., U.S. Pat. No. 4,369,298 (disclosing materials made from such synthetic resins). Other attempts have involved use of polycarbonate and polymethacrylate resins.

There have been problems using such substrates in a wide range of important applications.

For example, there is emerging recognition that many of the substrates provide less than optimal resistance to "wear and tear". That is, the substrates do not exhibit suitable resistance to abrasion, scratching, pitting and the like. Also, the substrates do not stand up well to significant solvent, fuel, light impact and/or salt exposure. These and other shortcomings have impaired more widespread use of a wide spectrum of substrates.

There have been attempts to improve the performance of such substrates.

One strategy has been to contact the substrates with a protective coat (sometimes called a "hard coat"). See e.g., U.S. Pat. No. 5,015,523, 4,229,228, 4,173,490, and 5,367,019 (reporting how to make and use various protective coats). As disclosed, the protective coat or layer helps to protect the substrate from damage. See also U.S. Patent Nos. 4,211,823, 4,284,685 and 4,355,135 (disclosing specific hard coats made from siloxane compositions).

However, many prior hard coats have been associated with substantial problems. Hard coated plastics and synthetic resins have been especially difficult to use.

In particular, many of the prior hard coats do not provide good protection under a variety of conditions. Maintenance of internal cohesion has been a major problem. These and other shortcomings continue to be a plague the field particularly when a transparent or translucent substrate is selected. Thus, use of many substrates in articles such as automotive lamp housings, instrument panel windows, rooftops, eyeglasses, sunglasses, safety goggles, and other applications has suffered.

More specifically, many of the prior hard coats do not provide good adhesion contact especially between the hard coat and the substrate. This defect can expose the substrate to damage from scratching, pitting, scaring, abrasion, chemical reaction and the like. Peeling and cracking of the coating is also problematic. These problems not only damage the substrate but can adversely impact light passage through many substrates. Such shortcomings have compromised substrate performance and decreased consumer value and confidence in many instances. Worse, use of such substrates may present a substantial hazard to the user.

It would be desirable to have compositions and methods for making coated substrates that provide good adhesion contact particularly between the substrate and the coat. More desirable would be to have substrate coatings and methods for making same that help to provide good adhesion contact. It would be particularly desirable to have coated substrates and coating compositions that feature good resistance to abrasion, scratching and other damage.

SUMMARY OF THE INVENTION

The invention generally relates to compositions and methods for coating a substrate. In one aspect, the invention features coated substrates with good adhesion contact between the substrate and a hard coat. Coating compositions and methods for making a variety of coated substrates are also provided. The invention has many useful applications including providing coated substrates with effective resistance against abrasion, scratching and other damage.

We have identified substrate coatings that provide good protection against damaging conditions. More particularly, we have identified methods for treating a wide spectrum of substrates that substantially enhances (or can provide in some cases) good adhesion contact between a substrate of interest and a hard coat. Such adhesive contact is surprisingly strong, durable, and helps to keep the coat and substrate cohesive. This feature of the invention provides several advantages, including boosting overall compatibility and bonding between the substrate and its protective hard coat. These and other benefits help protect substrates from a range of damaging (or potentially damaging) impact, temperature, water, gas, light, and/or salt conditions.

Practice of the present invention can significantly improve the performance of many substrates. For example, in one embodiment, the invention endows many polymer and synthetic resin substrates with good resistance to abrasion, scratches, pits, cuts, delamination, frictional wear, chemical and/or temperature damage. These advantages of the invention help to improve the strength and durability of the substrates, enhance product lifetime, and boost consumer confidence in many settings.

Accordingly, in one aspect, the invention features a coated substrate that is substantially cohesive and provides good resistance to damaging conditions as determined by one or a combination of standard tests. In one embodiment, the coated substrate includes a substrate; a first layer that includes inorganic filler particles; and a second layer with at least one compatibilizing agent in adhesive contact with the substrate. Typically, the inorganic filler particles are dispersed in at least one hydrolyzable silane as discussed below.

By the term "adhesive contact" or related term (including the plural form) is meant firm attachment between the substrate and at least the second layer of the substrate coating. Such adhesion contact can be detected (or quantified if desired) by performing a conventional adhesion test. Particular firm attachment according to the invention generally arises by bonding contact between the substrate and at least the second layer. As discussed below, in some invention embodiments, good adhesive contact involves firm attachment between the substrate and the first and second layers of the coated substrate. A preferred adhesion test is referred to herein as a "standard adhesion test".

A particular coated substrate of the invention features at least one of: i) a haze gain of less than about 5% as determined by a standard Taber Abrasion Test, preferably less than about 3% to 4%; and ii) an absent or negligible haze gain as determined by a standard high temperature humidity test. In this embodiment, the coated substrate includes, but is not limited to, substrates that are opaque, as well as those that are totally or partially transparent or translucent to incident light. As mentioned, the coated substrate includes at least one hydrolyzable silane. In one example of the invention, the hydrolyzable silane includes a first oxysilane (sometimes referred to as Component A). That first oxysilane has the following general Formula I below:

R^{3 χ}R^4y Si(OR²)⁴"^χ-^y

wherein,

2 i) R is an optionally substituted alkyl group having 1 to 20 carbons,

3 ii) R is an optionally substituted alkyl or epoxy group having 1 to 20 carbons;

4 in) R is an optionally substituted alkyl or alkoxy group having 1 to 20 carbons; and iv) x is 1 or 2, and y is 0 or 1,

2 3 4 wherein the alkyl group of R , R , and R are each the same or different.

The first oxysilane (Component A) represented by Formula I above can

3 include a variety of suitable epoxy groups as the R substituent. In one embodi the epoxy group has the following general Formula II or III below:

-(CH₂)_p-(O-CH₂CH₂)_r-O-CH₂-CH-CH₂

O π

m wherein p and q are each independently from 1 to 10 (inclusive), preferably 1 , 2, 3, 4, 5, or 6 and r is 0, 1, or 2.

In another embodiment, the hydrolyzable silanes of the coated substrate further include a second oxysilane (sometimes called Component B). A particular second oxysilane according to the invention has the following general Formula IV below:

IV wherein,

2 i) R is s aan optionally substituted alkyl group, unsaturated hydrocarbon, or aryl group having 1 to 20 carbons, ii) R is an optionally substituted alkyl or an alkoxy group of 1 to 20 carbons; and iii) x is 1 or 2,

2 5 wherein the alkyl group of R and R are each the same or different.

In one embodiment of the coated substrate, the inorganic filler particles

(sometimes called Component C) include at least one of an oxide, oxohydrate, nitride or carbide of Si, Al, Ti, or Zr. Examples of particular particles comprising or consisting of alumina or silicon are provided below. For some applications, inorganic filler particles made from hydrated alumina will be particularly useful.

As mentioned, the coated substrates of the present invention include at least one compatibilizing agent. Preferably, the substrates will have about one and generally one of such agents in most instances. Particular compatibilizing agents include a third oxysilane (sometimes referred to as primer, primer coat or layer) having the following general Formula V:

wherein, i) R is s aa group having 1 to 20 carbons in which the group is in adhesive contact with the substrate,

2 ii) R i ss aann aallkkyyll g group having from 1 to 20 carbons; and iii) x is 1, 2, or 3.

Reference to the primer shown in Formula V above being "in adhesive contact" with the substrate means that the primer is firmly attached to that substrate preferably via the R group. A preferred R group of the primer provides good adhesion contact with the substrate as determined in the standard adhesion test.

More particular R groups are specifically capable of providing good adhesive contact as determined by the standard adhesion test. Generally prior to adhesive contact, more particular R groups include at least one unsaturated carbon bond that can react by radical co-polymerization. Exemplary R groups include, but are not limited to, optionally substituted alkenyl and epoxy groups as discussed below.

Thus in one embodiment, the third oxysilane (primer) includes an R (epoxy) group having the general Formula II or III as shown above.

It will be appreciated that components of the coated substrate can be disposed with respect to each other as needed so long as intended performance results are achieved. For example, the second layer of the coated substrate can be positioned between the substrate and the first layer. In this embodiment, the first layer will typically be adjacent to and sometimes in adhesive contact with the second layer. In some instances however, coated substrates with other component positions may be more appropriate. As discussed, it is an objective of the present invention to provide coated substrates with good and effective protection from damage (or potential damage) including those conditions in which adverse impact or friction is likely. Such protection can be provided by one or a combination of strategies as follows.

For example, in one embodiment, the substrate is exposed to one or more treatment conditions sufficient to enhance (or provide for) good adhesion contact between the substrate and at least one of the first and second layers. As provided below, such conditions include contacting the substrate with at least one of a suitable electrical current or a reactive material, usually a reactive liquid such as an acidic or alkaline solution. In some instances, a combination of substrate treatments will be preferred to help achieve good adhesion contact. However in other cases, only one of such treatments will be needed. Choice of whether to expose a given substrate to one or more treatment conditions as described herein will be guided by recognized parameters including intended use and particularly by level of adhesion contact required for a particular application

The good adhesion contact between the substrate and at least the second layer of the coated substrate can provide additional benefits.

For example, in embodiments in which the adhesion contact is facilitated by formation of chemical bonds between the substrate and at least the second layer, particularly strong adhesion contact can be achieved. Such chemical bonds are often especially strong and may include non-covalent interactions, covalent bonds; or a combination thereof. In certain embodiments, the substrate is covalently bonded to at least the second primer layer and sometimes also to the first layer, thereby providing strong and durable coated substrate.

In another aspect, the invention features coating compositions preferably in good adhesion contact with a desired substrate. As an illustration, in one embodiment, the invention features a coating composition which includes: a first layer comprising inorganic filler particles dispersed in at least one hydrolyzable silane; and a second layer positioned between a substrate and the first layer. The second (primer) layer preferably includes at least one compatiblizing agent in adhesive contact with the substrate. Alternatively, or in addition, the substrate may be bonded to the inorganic filler particles, hydrolyzable silane or both.

A more particular coating composition is formulated to provide at least one of: i) a haze gain of less than about 5% as determined by a standard Taber Abrasion Test, preferably less than about 3% to 4%; and ii) an absent or negligible haze gain as determined by a standard high temperature humidity test.

Also provided is a synthetic resin or plastic substrate, preferably a polydiethyleneglycol bisallyl carbonate (CR-39™) substrate, coated in accord with this invention.

In one embodiment, the CR-39™ substrate is in good adhesive contact with at least one compatibilizing agent, preferably one of same, which agent typically makes up the primer layer. In this example of the invention, the coated CR-39™ substrate preferably has at least one of i) a haze gain of less than about 5% as determined by a standard Taber Abrasion Test, preferably less than about 3% to 4%; and ii) an absent or negligible haze gain as determined by a standard high temperature humidity test. In a still more specific example, the coated CR-39™ substrate is covalently bound to the primer layer.

In another aspect, the present invention provides an article of manufacture including or consisting of the coated substrates. Examples of such articles are provided below and include optical implementations such as those adapted for safety, ophthalmic, research, aviation, medical, photographic, transportation including automotive, recreational or military use. As disclosed in the USSN 60/206,592 provisional application, the invention provides useful anti-abrasion and anti-scratch resistant coatings for protecting a variety manufactured articles including automotive side windows, plastic prescription eyeglasses and sunglasses, and for use in automotive lamp housings, instrument panel windows and rooftops, as well as automotive side windows. As discussed below, specific coating formulations compare favorably and exceed results provided by prior coatings. In many instances, the coating of this invention are very effective in standard abrasion tests such as ANSI Z.26 and ANSI Z26.1.

As also provided in the USSN 60/206,592 provisional application, particular substrate coatings of this invention provide important advantages. For example, such coatings generally resist abrasion an order of magnitude better than the standard used in the substrate field. Such coatings can be formulated to resist incident radiation including ultra-violet, infra-red, and visible light. Such coatings can also be used to protect various other manufactured articles such as sportswear and especially clothing, footwear, skiing, hiking, tennis and eyewear implementations; sunglasses; prescription and corrective non-prescription eyewear; instrumentation, optical components, visors, miscellaneous OEM applications; and goggles especially those adapted for military, research or commercial use.

The invention provides other important advantages. For example, particular practice of the invention can increase the lifetime of many articles of manufacture, e.g., packaging implementations and particularly bottles (e.g., water bottles adapted for cooler use); electrical connecting devices and substrates, cookware including those adapted for microwave use; safety visors; windscreens; automotive use including parking light protection; window protection including skylights; sun roofs and other auto windows; hoods; toilet seats; etc.

As also provided, the invention is well-suited for glazing type applications such as those in which resistance to radiation (e.g., UV light), chemical and/or abrasion is needed. In particular, many of the substrate coatings of this invention can serve a "base coat" for applying one or more supplemental coats. Such coats are known in the field and may include anti-reflective coats, anti-glare coats, coats formulated to absorb or reflect particular light wavelengths including those in the visible, ultraviolet, infra-red and near infra-red ranges. Thus, another important feature of the invention is to provide an effective base coat foundation onto which other coats can be applied.

In another aspect, the invention provides methods for coating a desired substrate. Preferred substrates include those made from polymers including plastic or a synthetic resin. Such methods are useful for coating the entire substrate or only a part thereof as needed. Preferred methods include at least one, and preferably all of the following steps: a) exposing the substrate to conditions sufficient to increase (or provide for) adhesion contact between the substrate and at least one oxysilane, preferably the third oxysilane (primer) shown in Formula V above, b) contacting the substrate with at least one compatibilizing agent to form a primed substrate, c) contacting the primed substrate with inorganic filler particles dispersed in at least one hydrolyzable silane to coat the primed subsfrate; and d) curing the primed and coated substrate to form the coated polymer substrate.

In one embodiment, the method further includes cleaning the substrate preferably before step a) using one or combination of appropriate solvents, soaps, detergents and the like.

More specific conditions for providing for good adhesion contact between the substrate and the oxysilane (usually in the primer layer) includes exposing that substrate to the electrical current and/or reactive material described above. Also provided by the invention is a kit for performing the methods disclosed herein including coating a desired substrate.

Additional aspects and advantages of the invention are disclosed, infra.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows a substrate coated with a compatibilizing coating.

Figure 2 shows the substrate coated with the compatibilizing coating and a dispersed alumina powder-filled copolymer.

Figure 3 shows the cured anti-abrasion and anti-scratch coating on the plastic substrate.

Figure 4 schematically shows the steps in preparing the dispersed alumina- filled copolymer coating and the preparation and coating of the subsfrate, and the curing of the coating on the substrate.

Figure 5 A is a table showing data for abrasion resistance and haze gain tests.

2 A RC ( (AAddhheessiivvee AAbbrraassiioonn I Resistant Coating) refers to the substrate coating provided in Examples 1 and 2 below.

2

Figure 5B is a graph showing that the A RC coating exhibits less haze gain than a typical commercial coating.

Figure 5C is another table showing abrasion resistance and haze gain data for

2 the A RC coating (referred to as "Triton Systems" in the table).

Figure 6 is a table showing additional data for abrasion resistance and haze

2 gain tests using the A RC substrate coating. Figure 7 is a photograph demonstrating that visors coated in accord with the invention survive ballistic tests.

2

Figure 8 is a photograph showing that A RC coatings do not char or delaminate.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As discussed, the invention provides a wide variety of coated substrates, coating compositions, articles of manufacture, as well as methods for making same. The invention has many important uses including providing a spectrum of substrates with good resistance to abrasion, scratching, pitting, scaring, delamination, chemicals, temperature, and the like.

As also discussed, the coated substrates of this invention usually include a substrate, a first layer comprising inorganic filler particles dispersed in at least one hydrolyzable silane; and a second layer comprising at least one compatibilizing agent. Preferably, at least the second layer is in good adhesive contact with the substrate as determined by the standard adhesion assay.

Reference herein to a "standard adhesion assay" means a conventional tape adhesion test according to ASTM D 3359. Adhesion was evaluated via that test as follows. A section of a test sample such as a coated substrate (e.g., in film form) is crosshatched in 1/10" x 1/10" sections with a razor or other sharp blade. Tape is applied to the crosshatched section and rapidly removed at about a 90 degree angle. The test is performed using 3M #670M adhesive tape and adhesion is reported as the percentage of crosshatched squares adhering to the substrate after 10 tape pulls. Particular reference to "good" and or "effective" adhesion contact in this test means more than about 95% of the squares adhering to the substrate after 10 pulls, preferably more than about 98% of the squares adhering after 10 pulls, and more preferably about 100% of the squares adhering to the substrate after 10 pulls. Additionally preferred coated substrates according to the invention feature: i) a haze gain of less than about 5% according to the standard Taber Abrasion Test, preferably less than about 3% to 4%, more preferably between from about 0.1% to about 4% with between from about 0.1% to about 2-3% often being preferred; and ii) an absent or negligible haze gain as determined by a standard high temperature humidity test.

Reference herein to a "standard Taber Abrasion Test" or like term means that abrasion resistance test in accord with ASTM D1044. In this test, abrasive wheels are placed in contact with to a test sample such as a coated substrate of the invention.

Coated polycarbonate substrates are abraded with CA10F type abrasive wheels. Haze gain of the samples are generally measured after 100 and 500 test cycles. The wheels placed under a 500g load and abrade the surface for a set number of cycles. Abrasion resistance is represented as a haze gain or delta haze, i.e. the difference between the haze on the untested article and the haze after testing. Thus, a higher haze gain represents poorer abrasion resistance.

Reference in this application to a "standard high temperature humidity test" or related phrase means an adhesion test performed in the presence of water at or near the boiling point including steam. In particular, the test is conducted by the standard tape test (ASTM D 3359, see above) after the exposing a desired test sample such as a coated substrate of this invention to boiling water and steam. Samples were placed in boiling water. Tape adhesion tests were performed at 10 and 30 min intervals. For steam exposure, coated substrates or other samples were placed on a rack above a breaker or tank of boiling water. Steam condensed onto the substrates and Tape adhesion tests were performed at 30 and 60 min intervals.

By the term "good" and/or "effective" adhesion contact in the standard high temperature humidity test is meant more than about 95% of the squares adhering to the substrate after 10 pulls, preferably more than about 98% of the squares adhering after 10 pulls, and more preferably about 100% of the squares adhering to the substrate after 10 pulls.

Also preferred are coated substrates featuring at least one and preferably all of the following characteristics: i) absent or negligible haze gain or peeling as determined by a standard thermal and environmental exposure test; ii) negligible discoloration, blistering, softening, swelling, loss of adhesion, or other special phenomena as determined by a standard chemical resistance test; and iii) negligible crazing or cracking as determined by a standard ballistic test.

By the term "standard thermal and environmental exposure test" or related term is meant an accepted test to evaluate the long-term stability of a sample such as a coated substrate (e.g., in film form) during environmental exposure to thermal and humidity cycling tests (MIL STD 810 Method 507.3, Cycle 4). The coatings were stored in a controlled humidity chamber with temperatures ranging between 91 and 160°F and relative humidity between 14 and 80% for a period of 10 days. Following the exposure cycle, the coating is examined for bubbling, warping, adhesion loss, and haze gain.

Reference herein to a "standard chemical resistance test" or related term means a test according to ASTM D543. See Standard Practices for Evaluating the Resistance of Plastics to Chemical Reagents ASTM D543-95 pp. 25-30, (December, 1995); Standard Test Method for Effect of Household Chemicals on Clear and Pigmented Organic Finishes, ASTM D1308-87 pp. 37-38 (July, 1987); and FED Test Method Std. 406A; the disclosures of which are incorporated herein by reference.

Additionally preferred substrate compositions provide good chemical resistance according to the ASTM D543 test. That is, the coated substrates resist significant damage after exposure to test fluids recommended in that test. More preferred substrates coated in accord with the invention resist damage to harsher test fluids than recommended in the ASTM D543 test including hexane, toluene, methanol, acetone, methylethylketone (MEK), N-methylpyrolidinone (NMP), DEET (insect repellent), transmission fluid (Dexron), GBT airline oil, motor oil, and gasoline. Exposure is preferably for about 30 minutes. Following exposure, the compositions are examined for objectionable alteration of the surface such as discoloration, blistering, softening, swelling, loss of adhesion, or other special phenomena. The coated substrates show negligible objectionable alterations according to this test. Loss of adhesion is preferably determined by the standard adhesion test although use of the standard chemical resistance test for this purpose may also be useful for some applications.

Additionally preferred coated substrates provide good resistance to impact as determined by the standard ballistic test. By the phrase "standard ballistic test" is meant a test conducted per MIL-STD-662. Particular compositions of the invention show negligible crazing, cracking, spalling or delamination after impact. See Figure 7 in the Drawings.

For example, in embodiments in which a particular coated substrate is a coated polycarbonate ballistic lens, visor or related test sample, that substrate is manipulated to receive repeated (4 shot) ballistic impacts with 0.22 caliber fragment simulating projectile at 550 to 560 feet per second. The substrate coatings or other test samples are then examined by inspection. As shown in Figure 7, a visor coated in accord with this invention showed no crazing or cracking after the ballistic impact.

Also preferred are coated substrates that good resistance to flame or charring. See Figure 8 (showing a coated substrate resisting charring). More preferred are those coated substrates featuring good resistance as determined by a standard flame resistance test.

Reference to a "standard flame resistance test" or related phrase herein means a cone calorimetry test conducted in accord with ASTM El 354. In embodiments of the invention in which the substrate is a polycarbonate (PC) substrate, cone calorimetry tests were usually performed on bare PC and coated PC. Time to ignition, Total heat released CO yield and the average heat release rates (HRR) are all measured to determine the flammability of coated and uncoated polymer substrates. Good flame resistance in the test was exemplified by at least one and preferably all of the following characteristics as determined by the standard flame resistance test: i) a sustained ignition of at least about 110 seconds; ii) total heat

2 release of less than about 65 MJ/m ; iii) a CO yield of less than about 0.180 kg/kg;

2 and iv) an average heat release rate of less than about 260 kW/m (180seconds) or less than about 170 kW/m² (300s).

Test samples mentioned in the foregoing standard tests generally include a substrate coated with at least a second primer layer of this invention. The test sample may further include the first layer in which case the sample will often be referenced as a "hard coated" substrate.

It will be understood that in the foregoing standard tests, inclusion of a control sample (usually neat substrate) will be helpful in identifying and quantifying (if needed) the good adhesive contact provided by this invention. However when the performance characteristics of the control sample are already known in a particular test it may not be necessary to use the control sample in that test.

In invention embodiments in which the test sample essentially includes the second layer, one or all of the foregoing standard tests can be employed to identify components that provide good adhesive contact between the substrate and at least that second primer layer. Such components include particular oxysilanes, solvents, and inorganic filler particles as well as combinations thereof. The standard tests are specifically useful for identifying suitable third oxysilanes and especially good side groups (e.g., the R group shown in Formula V) thereon provide good adhesive contact between a substrate of interest and the second primer layer. In certain invention embodiments, it will often be useful to use transparent or translucent substrates such as those made wholly or in part from plastics. Such plastic substrates typically face a wide variety of mechanical , environmental, and other hazards in normal day-to-day use. For lenses applications, preferred substrate coatings must maintain hardness and reliable adhesion to the substrate material over a reasonable life time to provide adequate protection and durability for a reasonable service life. For aircraft, automobile, and other transportation windows, coatings must meet similar hardness and adhesion requirements. For transportation windows, a number of other properties are highly desirable including resistance to fuels, oils, cleaning solvents, and a variety of other fluids; impact and ballistic threats; and flammability. Increasing the resistance of the base substrate to these various threats increases the service lifetime and the overall attractiveness of the material for these applications. A number of standard tests, including those specially mentioned herein, are used to determine and, if needed, quantify, the resistance of protective coatings to the various threats encountered in day to day use.

The present invention is flexible and compatible with a range of specific inorganic filler particles (Component C). Included are inorganic filler particles that consist of or include alumina or silica in which the particles are preferably present in the first layer in an amount of from between about 1% (wt/wt) to about 80% (wt/wt), preferably from about 5% (wt/wt) to about 70% (wt wt). Additionally preferred particles including those derived from alumina have a diameter of from between about 1 to about 200 nanometers, preferably about 1 to about 100 nanometers, more preferably about 2 to about 50 nanometers.

A more specific Component C according to the invention is a colloidal ceramic particle having an average particle diameter between 1 and 150 nanometers. A variety of oxides are suitable so long as they are compatible with Components A and B. Suitable particles include but are not limited to oxides or oxyhydradates of silicon, aluminum, titanium, zirconium, antimony, or other transition metals or combinations thereof. A wide variety of commercial, acidic, nanoscale (4-20nm) silica dispersions that are suitable for use as inorganic filler particles in the coating system are available commercially such as of the Nalco Chemical Co. of Naperville, IL; Du Pont, Inc. (marketed under the trade name Ludox), Nissan Chemical Co., and a number of other suppliers. These silica dispersions are available in a variety of suitable solvents such as aqueous dispersions such as Nalco 1034, methanol dispersions such as Nissan M-ST, iso-propanol dispersions such as Nissan IPA-ST, etc. A variety of other metal oxide filler particles can be produced can be produced via the controlled hydrolysis, condensation, and stabilization of a variety of metal compounds such as, titanium tefraisopropropoxide, titanium tetrabutoxide, zirconium tefraisopropropoxide, zirconium tetrabutoxide, aluminum triisopropoxide, aluminum tributoxide, or the dispersion of commercially available synthetic nanoscale alumina particles, mineral or pseudo-mineral sources of a hydrated or partially hydrated ceramic oxides such as gibbsite or bohemite, etc. Component C is preferably an oxide or partially hydrated oxide of silicon or aluminum.

See also the U.S. Pat. Nos. 5,015,523; 6,008,285; and references disclosed therein for disclosure relating to suitable inorganic filler particles.

As discussed, the coated substrates of this invention generally include at least one suitable hydrolyzable silane which silane preferably includes a first oxysilane as shown above in Formula I (Component A) and a second oxysilane as shown above in Formula IV (Component B).

A particular coated substrate of this invention includes at least one hydrolyzable silane which silane is present in the first layer in an amount generally less than about 20% (wt/wt).

By the term "hydrolyzable silane" or related phrase including the plural is meant silanes capable of forming hydrolyzates typically by contact with pure water or a mixture of water and an appropriate solvent. A wide variety of acid or base catalysts can be used to promote the hydrolysis and condensation of silanes to form hydrolyzates. Influence of various catalysts on the hydrolysis and condensation process, the relative rates of the hydrolysis and condensation processes under various reaction conditions, and strategies for controlling the structure and reactivity of a variety of silane and other inorganic hydrolyzates are discussed in great detail by Her in The Chemistry of Silica (Wiley -Interscience, New, York, 1979) and Brinker and Scherer in Sol-Gel Science (Academic Press, San Diego, 1990); the disclosures of which are incorporated herein by reference.

Silane hydrolyzates formed under acidic conditions yield materials with excellent transparency in the final cured coating and superior shelf life (i.e. are less prone to premature gelation). These hydrolyzates are preferably formed and stored at a pH of between 3 and 6. The use of a carefully controlled amount of water during the initial stages of the formation of the hydrolyzate can have an important influence on its resultant structure. The initial stages of hydrolyzate formation are carried out in the presence of between 0.5 and 100 molar equivalents of water per silane, preferably between 1.5 and 50 molar equivalents, most preferably between 4.5 and 18 molar equivalents.

Particular formation of the silane hydrolyzate may be carried out in by use of one or a combination of strategies. For example, a suitable hydrolyzate can be formed by reaction of silanes with water in the presence of an acid in a separate reactor, prior to the addition of any of the other coating components. In many cases, part or all silanes can be converted to silane hydrolyzates within an acidic dispersion of the inorganic filler particles (Component (C)). A wide variety of commercial, acidic, nanoscale (4-20nm) dispersions of silica particles are available commercially such as of the Nalco Chemical Co. of Naperville, IL; Du Pont, Inc. (marketed under the trade name Ludox), Nissan Chemical Co., and a number of other suppliers. A variety of other acidic, nanoscale (l-lOOnm) dispersions of inorganic particles can be formed by the careful hydrolysis, condensation and stabilization of metal containing precursors, or the dispersion of a variety of synthetic or mineral based powders. Formation of the silane hydrolyzate in the presence of the inorganic filler particles has some potential advantages. Formation of the hydrolyzate in the presence of Component (C) enhances the extent of bonding between the hydrolyzate(s) and the surface of the inorganic filler particle. Direct bonding between the silanes of the hydrolyzate and the filler particles will benefit the overall abrasion properties and improve the stability of the particles in the formulation. With bonding of the silanes of Components A and B to the filler surface, the inorganic (e.g. siloxane) and organic (e.g. ring opened epoxy polymers) that form upon curing will both be tethered to the filler via covalent bonds. Formation of the silane hydrolyzate is preferably accomplished by adding an acidic dispersion of inorganic particles to Component (A), Component (B) or a combination thereof.

In one invention embodiment, the first oxysilane represented above in Formula I (Component A) includes from between about 5% (wt/wt) to about 85% (wt/wt) of total solids in the first layer, preferably about 10% (wt/wt) to about 65% (wt/wt), more preferably about 20% (wt/wt) to about 60% (wt/wt).

Preferred for many applications are coated substrates in which the first oxysilane shown above in Formula I (Component A) is

3-glycidoxypropyltrimethoxysilane (GPTMS), 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 3-glycidoxypropylmethyldiethoxysilane,

3 ,4-epoxy cyclohexy lfrimethoxy silane, 3 ,4-epoxycyclohexy ltriethoxy silane,

3,4-epoxycyclohexylmethyldimethoxysilane,

3 ,4 epoxycyclohexylmethyldiethoxysilane, 2-glycidoxyethylfrimethoxysilane, glycidoxymethyltrimethoxysilane, epoxypropyltrimethoxysilane, or epoxybutyltrimethoxysilane.

Glycidoxypropyl- and 3, 4-epoxycyclohexyltrialkoxy silane are especially preferred first oxysilanes (Component A) according to the Formula I.

As mentioned previously, many coated substrates of this invention include a second oxysilane as shown above in Formula IV (Component B). Preferably, that component includes from between about 5% (wt/wt) to about 85% (wt/wt) of total solids in the first layer, preferably about 10% (wt/wt) to about 50% (wt/wt), more preferably about 10% (wt/wt) to about 40% (wt/wt) of the total solids.

It is important that the Component B be generally compatible with at least the first oxysilane (Component A) and the inorganic filler particles (Component C). By the term "compatible" is meant that combination of one component with the other produces a composition with desired performance characteristics. A composition of the invention is used herein to denote a coated substrate, coating composition, article of manufacture and the like.

Examples of acceptable second oxysilanes according to the Formula IV shown previously include tetraethoxysilane, teframethoxysilane, tetrapropoxysilane, tetraisopropylsilane tefrabutoxysilane, methyltriethoxysilane, methylfrimethoxysilane, methyltriproxysilane, methylfriisopropylsilane methyltributoxysilane, ethyltriethoxysilane, ethyltrimethoxysilane, ethyltriproxysilane, ethyltriisopropylsilane, ethyltributoxysilane, propyltriethoxysilane, propyltrimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, octyltriethoxysilane, octyltrimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, ally ltriethoxy silane, allyltrimethoxysilane, 3 -aminopropyltriethoxysilane, 3 -aminopropyltrimethoxysilane, 3 -methacryloxypropy ltriethoxy silane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3 -chloropropylfrimethoxy silane, 3 -cyanopropy ltriethoxy silane, and 3-cyanopropyltrimethoxysilane.

An especially preferred second oxysilane for many applications is tetraethoxysilane, methylfrimethoxysilane, or methyltriethoxysilane. As discussed, the coated substrates of this invention also include a third oxysilane (primer) represented by the Formula V shown previously. In a particular example, the primer is more specifically represented by the following Formula Va:

Va wherein, i) R is a group having 1 to 20 carbons and includes at least one of an optionally substituted unsaturated hydrocarbon; or a mercapto, cyano, isocyano, amino, imino, hydroxyl, acryloxy, epoxy, or methacryloxy group, the group being in adhesive contact with a substrate,

2 n) R is an optionally substituted alkyl group having from 1 to 20 carbons; and iii) x is 1, 2, or 3.

In a particular embodiment of the third oxysilane (primer) shown above in Formula Va, the unsaturated hydrocarbon is an alkenyl group such as vinyl, styryl, or allyl. More specific examples of such primers include vinylfriethoxysilane, vinyltrimethoxysilane, vinyl(methyl)dimethoxysilane, vinylpropyldiethoxysilane. Also included are 3-chloropropyl trialkoxysilanes and 3- mercaptopropyltrialkoxysilanes.

In embodiments in which the third oxysilane (primer) includes an epoxy group, particularly as the R group shown above in Formula Va above, the epoxy group preferably has the general Formula II or III described previously. Specific examples of such primers include glycidoxypropyltrialkoxy silane and 3,4- epoxycyclohexyl-trialkoxysilane.

See also the U.S. Pat. No. 5,015,523 and references disclosed therein for examples of other suitable oxysilanes including primer and hard coat compositions for use with the present invention. By the phrase "compatibilizing agent" or related term or phrase is meant an agent with at least one suitable primer and at least one suitable solvent (or solvent system). Preferred solvents dissolve or disperse the primer to make the compatibilizing agent. Alternatively, use of other solvents or solvent systems may be more appropriate for some invention embodiments. Optionally, the compabilizing agent may include one or more additives known in this particular field including anti- reflective additives. See e.g., the U.S. Pat. No. 5,015,523 for disclosure relating to such additives.

In particular embodiments of the present invention, addition of one or a combination of solvents to the coating formulations (including formulations for making the first and second layers) will help provide stability and adjust viscosity properties of the coating to a desired range. When used, a preferred solvent or solvent system will be referred to as Component D.

In this example of the invention, much of the total amount of solvent present in the total coating formulation is added to the formulation as the dispersing medium for the inorganic filler particle of Component C. Depending upon the pot life desired, the coating may be diluted with a variety of solvents. Solvents improve pot life by serving as a diluent or by reacting, interacting, or exchanging with more reactive surface groups on the silane hydrolyzates and /or inorganic filler particles. A variety of solvents can be added so long as they are compatible with Components A, B, and C, and the desired substrate, including, but not exclusively limited to substantially polar solvents e.g., water, ethanol, methanol, n-propanol, isopropanol, n-butanol, sec- butanol, isobutanol ethylene glycol, Alkoxyethanols (e.g. methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, etc. also commonly known as Cellosolve). Also included are diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethyl acetate, butylacetate, propylene carbonate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, amides such as dimethylformamide and dimethylacetamide, toluene, xylene, alkanes, and compounds containing halogenated groups such as Freon and dichloromethane.

As mentioned, a particular coating composition of the invention includes a first layer with suitable inorganic filler particles dispersed in at least one hydrolyzable silane; and a second layer comprising at least one compatiblizing agent in adhesive contact with a substrate. Preferably, that coating composition advantageously provides the substrate with at least one of a haze gain of less than about 5% according to the standard Taber Abrasion Test, preferably less than about 3% to 4%, more preferably between from about 0.10% to about 4% with between from about 0.10% to about 2-3% often being preferred; and ii) an absent or negligible haze gain as determined by a standard high temperature humidity test.

Also preferably, the coating composition provides good flame resistance. In embodiments in which the composition is in good adhesion contact with a polycarbonate substrate, such favorable flame resistance includes at least one of the following characteristics as determined by the standard flame resistance test: i) sustained ignition of at least about 110 seconds; ii) total heat release of less than about

2

65 MJ/m ; iii) a CO yield of less than about 0.180 kg/kg; and iv) an average heat

2 2 release rate of less than about 260 kW/m (180seconds) or less than about 170 kW/m (300s).

As discussed, the present invention relates to the application of a durable and tenaciously adherent protective coating to a wide variety of coated substrates such as polycarbonate and other plastic optical subsfrates. As also discussed that coating can be applied to a desired by one or a combination of strategies in accord with this invention.

In a particular embodiment, the invention involves pretreatment of the substrate, application of the primer (second layer) to promote adhesion, and the application of an abrasion resistant coating (first layer) containing the hydrolyzable silanes and inorganic filler particles. In accord with these objectives of the invention, the substrate can be pre-treated which includes simple washing and cleaning procedures. Use of water, soap, detergent or organic solvents are generally preferred for many substrates.

Significantly, the invention features use of alternative or supplemental treatment conditions that preferably modify, usually chemically, the substrate surface to promote good adhesion contact. We have found that preferred conditions include one or a variety of treatments e.g., wet chemical treatment and particularly treatment with strong acidic or basic solutions; and treatment with an electrical current, preferably a corona discharge or low pressure plasma. More preferred treatment conditions according to the invention prepare or "prime" the substrate for successful application of the primer and abrasion resistant (hard) coatings. Without wishing to be bound to any theory, the substrate treatment methods are believed to provide good adhesion contact by one or more of increasing substrate surface area, enhancing substrate surface energy, and modifying the substrate surface. These features of the invention help to provide sites compatible with at least the primer layer and preferably the primer and hard coating layers.

A preferred subsfrate treatment condition for many applications is a corona discharge.

1 2

As mentioned, the primer is preferably a silane of the form, R xSi(OR )4-x, where x is from 1 to 3; R is an organic group wherein one of the organic group containing, prior to reaction, some degree of unsaturation such as a vinyl, allyl, acryloxy, methacryloxy. Preferred are unsaturated bonds that are capable of

2 interacting with or bonding to the pretreated substrate and R is a hydrocarbon group, preferably between 1 and 4 carbons. The thickness of the primer layer is less than about 15 microns, preferably 0.01 to 5 microns, with less than about 1 micron being preferred for many applications. The silane of the primer may be applied directly to the substrate or dispersed in an appropriate solvent, preferably dispersed in a solvent at a level between 0.05% and 10%, preferably between 1% and 7%.

The cured abrasion resistant coating afforded by the first layer discussed

3 4 2 3 above preferably includes (i) a silane of the form R xR ySi(OR )4-x-y, where R is an

₄ alkyl group or a group with an epoxy moiety and R is a hydrocarbon group or an

₅ 2 ₅ alkoxy group, (ii) a silane of the form R χSi(OR )4-x, where R is an alkyl group or an alkoxy group not containing an epoxy group and x may equal 1 or two, (iii) inorganic filler particles between 1 and 150 nanometers in diameter, and (iv) solvents selected to stabilize the various components of the coating and adjust the viscosity of the coating to a level suitable for the desired application method.

Suitable alkyl groups are 1 to about 20 carbons in length, preferably 1 to about 15 carbons with about 1 to 5 carbons often being preferred. Such groups can be branched or unbranched as required. As used herein, the term alkyl unless otherwise modified refers to both cyclic and noncyclic groups, although of course cyclic groups will comprise at least three carbon ring members. Typical examples include methyl, ethyl, n-propyl, i-propyl, n-butyl, t-butyl, i-butyl, pentyl, i-pentyl, hexyl, octyl and nonyl. Exemplary cyclic alkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl and the like.

Specific reference herein to a "hydrocarbon" or "hydrocarbon group" means alkyl unless otherwise specified.

Typical alkenyl and alkynyl groups have one or more unsaturated linkages and typically from 2 to about 12 carbon atoms (branched or single chain), more preferably 2 to about 8 carbon atoms, still more preferably 2, 3, 4, 5, or 6 carbon atoms. The terms alkenyl and alkynyl refer to both cyclic and noncyclic groups, although straight or branched noncyclic groups are generally more preferred. Reference herein to an unsaturated hydrocarbon means an alkenyl or alkynyl unless otherwise provided. Preferred of unsaturated hydrocarbons are typically from 2 to about 10 carbon atoms in length, more preferably 2 to about 8 carbon atoms, still more preferably 2, 3, 4, 5, or 6 carbon atoms in length. Typical of such alkenyl groups include vinyl, styryl, allyl, 2-butenyl, 2-pentenyl, and 2-hexenyl groups. Examples of suitable alkynyl groups include acetynyl and propargyl groups.

By the term "alkoxy group" is meant a group having one or more oxygen linkages and from 1 to about 12 carbon atoms, preferably from 1 to about 8 carbon atoms, more preferably 1, 2, 3, 4, 5 or 6 carbon atoms. Typical of such groups include methoxy, ethoxy, propoxy, acryloxy, butoxy, t-butoxy, and pentoxy.

Typical halo groups include fluorine, chlorine, bromine, and iodine.

Typical aryl groups include phenyl, benzyl, napthyl, phenanthryl, anthracyl, and fluorene groups. Examples of aralkyl groups include the above listed alkyl groups substituted with phenyl, napthyl, and phenanthryl groups.

The term "oxysilane" is used herein to refer to any one of the first, second or third oxysilanes discussed above. See Formulae I, IV, V and Va as shown above.

By the phrase "optionally substituted" is meant a substituted or unsubstituted substituent group. Preferred substitution groups include alkyl, preferably methyl, ethyl, and propyl; halo, preferably chloro and bromo; amino, cyano, isocyano, mercapto, hydoxyl, imino, alkoxy, preferably methoxy; and the like.

As discussed, the invention encompasses methods for improving the abrasion resistance, durability and environmental stability of plastic substrates, such as transparent or translucent plastic subsfrates by preparing or pretreating the substrate, applying a primer layer to the substrate and applying and curing a protective hardcoat layer on the substrate. The invention is fully compatible with a wide spectrum of substrates including those made wholly or in part from plastics or synthetic resins. For example, plastic substrates may be any of a number of materials commonly used in eyeglasses or safety goggles, or as window materials or housings in buildings or transportation vehicles such as automobiles, buses, trains and aircraft. These materials include, but are not limited to, transparent plastics, polycarbonates and acrylics (both stretched and cast), CR-39™ plastic (i.e. polydiethyleneglycol bisallyl carbonate), proprietary high index plastics and polycarbonates used in the ophthalmic industry for making very thin lightweight lenses, polyester, acrylonitrile-butadiene-stryrene, etc.

Methods for making lenses from these and other specific materials is well understood. In general, the methods generally include (a) casting a monomer mixture into a mold, heating the mold to a predetermined temperature for a predetermined time, removing the material from the mold, and then post curing the plastic material mold to a predetermined temperature for a predetermined time to obtain the lens; or (b) injection or compression molding a polymer resin, e.g. acrylic or polycarbonate resins, into a lens configuration. Windows, other large articles, or articles of complex shape may be cast, stretched, or thermoformed.

In many instances, pre-freatment particularly by cleaning a selected substrate will facilitate good adhesion contact. Such cleaning steps can be performed by one or a combination of steps.

For example, the substrate can be properly cleaned to remove any dirt or organic matter that may prevent good adhesion contact. A variety of solvents, detergents, and methods, e.g. the use of an ultrasonic cleaning bath, familiar to those skilled in the art may be used to adequately clean the substrate. Preferably, the subsfrate is cleaned by washing with methanol followed by isopropanol. Of course, if the substrate of interest is already cleaned such steps may not always be necessary. In accord with the invention, the substrate is subsequently exposed to treatment conditions sufficient to enhance (or provide for) good adhesion contact. Without wishing to be bound to any theory, preferred conditions generally achieve at least one of: increase the substrate surface area to promote physical interlock with the substrate; increase the substrate surface energy, and improve wetting of the substrate by subsequent primer and coating layers. Such treatment conditions preferably also create a plurality of substrate surface groups and sites that are capable of interacting or reacting with components to achieve good and effective adhesion contact. As discussed, such contact binds the primer and coating layers to the substrate, thereby enhancing protection and performance of the substrate.

Particular treatment conditions include, but are not limited to, corona discharge, low-pressure plasma treatment, and wet chemical treatments. Conventional methods for such treatment are described by Chan in Polymer Surface Modification and Characterization (Hanser, New York, 1993) and Pocius in Adhesion and Adhesives Technology (Hanser, New York, 1997); the disclosures of which are hereby incorporated by reference.

Generally, a suitable corona treatment system includes a high- voltage and high frequency generator, an electrode, and an insulated, grounded metal roll or fixture. The system behaves as a capacitor and corona occurs when high voltage is applied between the electrode and fixture to cause ionization of the air. The atmospheric pressure plasma that forms is called corona discharge. Electrons, ions, excited neutrals, and photons present in the discharge impact and interact with the substrate surface. Without wishing to be bound to theory, it is believed that the net result is roughening and an increase in the polymer surface area. The, ions, excited neutrals, etc. in the discharge can also react with the polymer surface to form radicals that rapidly react with ambient oxygen and moisture. Also believed is that such electrical treatment of the subsfrate substantially increases the surface energy of the polymer and creates of surface groups that can interact and /or react with subsequent primer and coating layers. Although a corona discharge is often suitable for most invention applications, in some embodiments it may be more useful to treat a particular substrate with a low- pressure plasma. In this illustration of the invention, the plasma allows more carefully controlled treatment of polymer surfaces with ions and reactive species. This process is usually carried out at reduced pressure and the apparatus generally consists of a vacuum chamber, a gas inlet, an rf or microwave frequency generator and an electrically conductive coil or set of electrodes. Species in the plasma can also react with the polymer surface to form radicals just as in the corona discharge. The ability to use a variety of gas sources in a plasma system allows the formation of a wide variety ofsurface groups such as surface oxidation in oxygen plasmas, surface amine groups in ammonia plasmas, surface fluorination to impart hydrophobic properties from fluorocarbon plasmas, etc.

Alternatively, or in addition, suitable treatment conditions can include wet chemical treatments. Included are etching substrates with sfrongly alkaline or acidic solutions so as to increase substrate surface energy and form oxidation sites similar to those formed in plasma and corona treatments.

As discussed, a preferred treatment condition for achieving good adhesion contact is exposure to an electrical current and particularly a corona discharge. Such conditions generally improve adhesion of the substrate to the second and first layers particularly under extreme conditions such as boiling water and steam. However, in some invention embodiments such treatment conditions may not be necessary depending on the particular substrate, primer, coating, and adhesion contact strength desired for a particular application.

As an illustration, it is possible to directly hard coat certain substrates made synthetic resins. That is, the substrate does not need the primer or associated treatment conditions to provide good adhesion contact between the subsfrate and the hard coat (first layer). A specific example of such a substrate is (polydiethyleneglycol bisallyl carbonate) CR-39™. In contrast, it has been found that polycarbonate substrates generally require exposure to the treatment conditions, particularly a corona, and application of the primer to achieve good adhesion contact. Choice of whether to apply a desired hard coat layer to a substrate of interest will be guided by recognized parameters including intended use of the coated substrate, and particularly the adhesion and durability required.

The term "priming" especially in reference to a substrate means application of a chemical or coating that favorably changes adhesion properties of the substrate. Silane coupling reagents are commonly used to improve compatibility between inorganic and polymeric materials and to tailor the interfacial properties in glass- polymer composites.

In accord with the objectives of this invention, one or a combination of suitable silanes is chosen that can preferably react or interact with sites on the initial substrate, usually a polymer substrate; or sites created during the pretreatment or treatment conditions described above. These compounds include but are not limited to, silanes containing double bonds capable of interacting with species created on the surface during pretreatment such as vinyl-, allyl-, acryloxy-, or methacryloxy- trialkoxysilanes; chloroalkyl groups capable of interacting with species created on the surface during pretreatment such as 3-chloropropyl trialkoxysilane; mercapto groups capable of interacting with species created on the surface during pretreatment such as 3-mercaptopropyl trialkoxysilane; epoxy groups capable of interacting with species created on the surface during pretreatment such as glycidoxypropyl- and 3,4 epoxycyclohexyl- trialkoxy silane; isocyanate groups capable of interacting with species created on the surface during pretreatment such as 3-isocyanatopropyl trialkoxysilane. Silanes with double bonds are the preferred reagents and vinyltriethoxysilane generally the most preferred reagent for many invention applications.

Preferred use of the primer involves application as a solution that includes between about 100% (wt/wt) and about 0.05% (wt/wt) of the primer in an appropriate solvent, preferably about 0.1% (wt/wt) to about 25% (wt/wt), more preferably about 0.5% (wt/wt) to about 5% (wt/wt). A wide variety of compatible solvents can be used, so long as the solvent does not react with or otherwise modify groups on the silane or substrate surface important to adhesion. Suitable solvents include, but are not limited to, ethanol, methanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol ethylene glycol, Alkoxyethanols (e.g. methoxyethanol, ethoxyethanol, propoxyethanol, butoxyethanol, etc. also commonly known as Cellosolve), diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, ethyl acetate, butylacetate, propylene carbonate, ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, amides such as dimethylformamide and dimethylacetamide, toluene, xylene, alkanes, and compounds containing halogenated groups such as Freon and dichloromethane.

A preferred thickness for the primer layer (second layer) is less than about 15 micrometers, preferably less than about 10 micrometers, more preferably less than 1 micrometer, with a thickness approaching a monolayer being especially preferred for many invention applications.

In one invention embodiment, the substrate is rinsed with pure solvent after the application of the primer solution in order to remove any excess, weakly bound silanes from the surface to insure a reliable interface between the coating and substrate. Maintaining the purity and reactivity of the silane compound is important to achieving optimal adhesion. Exposure of the silanes to moisture or any other potential reactants during the application, rinsing, and drying procedures can reduce the level of adhesion to the substrate. Primers are preferably prepared in and rinsed with anhydrous solvents.

Application of the primer to a desired substrate can be achieved by one or a combination of conventional strategies including flow, dip, spray, roller, or other methods familiar to those working in this field. The primer is preferably applied via dip coating or flow coating. The primer applied to a properly treated substrate provides a protective coating with a combination of adhesion, adhesion in boiling water and steam, and abrasion resistance superior to the current state of the art.

As mentioned previously, it is an object of this invention to coat a desired subsfrate with a durable hard coating. Preferably, that coating is applied onto the primer composition. A more preferred hard coating is provided as the second layer and includes at least one and preferably all of the following components:

3 4 2 1. Component (A):a hydrolyzate of silanes of the form R xR ySi(OR )4-x-

3 4 y, where R is an alkyl group or group containing an epoxy group and R is a hydrocarbon group or an alkoxy group, makes up between 85 and 5 wt% of the total solids in the coating, preferably between 50 and 20 wt% of the total solids.

5 2 2. Component (B): a hydrolyzate of silanes of the form R χSi(OR )4-x, where R is an alkyl group or an alkoxy group preferably without an epoxy group and x may equal 1 or two. Also preferably, the component makes up between 85 and 5 wt% of the total solids in the coating, preferably between 40 and 10 wt% of the total solids.

3. Component (C): inorganic filler particles, make up between 65 and 5 wt% of the total solids in the coating, preferably between 50 and 20 wt%.

4. Component (D): The solvent makes up between 99 and 50 wt% of the total solution weight, preferably between 90 and 65 wt %.

Optionally, one or additional additives familiar to those skilled in the art may be added to the coating to enhance their usefulness including but not limited to leveling agents, ultraviolet light absorbers, light stabilizers, thixofropic agents, and other surface active agents. The addition of other compounds known to those familiar with the chemistry of epoxy resins, siloxane resins, and sol-gel systems may be added to the coating solution including catalysts and cross-linking reagents, in order to adjust the curing time, flexibility, and other properties of the coating. It is understood that any of these additives can be added so long as they do not significantly reduce the transparency, adhesion or abrasion resistance of the final coating.

As mentioned, preferred third oxysilanes (primer) are capable of participating in radical co-polymerization reactions. Such reactions are known in the field and usually include radical assisted polymerization of a monomer. See generally J. McMurry in Organic Chemistry, 3rd Ed. Chpt. 31 (Brooks/Cole Publishing Co. Pacific Grove, CA). Without wishing to be bound to theory, it is believed that an effective radical co-polymerization reaction involves forming one or more covalent bonds between the substrate and the coat, preferably between the substrate and the primer layer, and more preferably between the subsfrate of interest and the R group of the third oxysilane (primer) shown above in Formulae V and Va shown previously.

Suitable radical co-polymerization in accord with the invention involves exposing the substrate to pre-treatment and/or treatment conditions outlined above. As discussed already, such conditions have been found to provide or enhance good adhesion contact between the substrate and at least the primer layer and for some applications between the substrate and the first and second primer layers. More particular treatment conditions will help form and/or help stabilize the formation of free radicals from the subsfrate surface. Without wishing to be bound to any theory, given the concentration of silane and the solvents used for many primers of the invention, the degree of polymerization of the primer compound is usually limited and consists of oligomeric species of several repeat units or in all likelihood even fewer units.

Acceptable bonds between the subsfrate and at least the second primer layer will generally involve bonding between carbon, silicon, and oxygen atoms e.g., hydrogen bonds, ionic bonds, covalent bonds between carbon and silicon atoms, and hydrophobic or Van der Waals attraction, etc. Particular methods for making substrate coatings have been discussed and are provided in more detail in the Examples below. Significantly, specific methods use a coating bath that is generally stable over time and can be "topped up" without substantially changing the concentration of any substituents of the bath. Also significantly, the methods provide for fast cure times (i.e. about an hour or less), thereby allowing for quick turnover of materials.

Some of the following discussion up to and including Examples 1-3 is taken from the U.S. Provisional Application U.S.S.N. 60/206,592 filed on May 23, 2000 and entitled "Compositions and Methods for Coating Substrates". Some of the discussion describes how to make and use a variety of more specific coated substrates.

One substrate coating ("hard coat") in accord with this invention is an engineered aluminosilicate/epoxide nanocomposite that provides at least one of good adhesion, abrasion resistance, haze gain, chemical resistance, humidity test, thermal cycling and ballistic impact resistance according to standard tests referenced herein. See the Examples and the Drawings.

In one embodiment, the hard coat includes at least one and preferably all of the following components: at least one type of alumina or hydrated alumina powder, at least one alkoxysilane (disclosed below as first and second alkoxysilanes), and at least one compatibilizing agent such as those oxysilanes having reactive chemical groups described below.

As an illustration, a preferred hard coat includes less than about 20% by weight, preferably less than about 15% by weight, and more preferably about 8% to 11% by weight of the alumina; less than about a 10 molar ratio, preferably between from about a 5 to 3 molar ratio of at least one suitable first and second alkoxysilane. Typically, the hard coat is thinned to a desired consistency with about 3% to 20% alcohol (or other suitable solvent) to make the substrate coating solution. In a more particular embodiment, the hard coat further includes at least one suitable compatibilizing agent in an amount less than about 20% by weight, preferably less than about 10% by weight, more preferably less than about 3% to 10% by weight. In a preferred embodiment, the compatibilizing agent in the hard coat forms a mono- or near monomolecular layer particularly in contact with the substrate to be coated. Thus, hard coats that include minor amounts including trace quantities of the compatibilizing agent are contemplated and within the scope of this invention.

As an illustration of the invention, the compatibilizing agent can be provided to the hard coat by contacting the surface of the substrate to be coated with the agent (or combination of different agents). Generally, that contact can be suitably provided by immersing the surface in a bath that includes the compatibilizing agent dissolved in at least one suitable solvent such as alcohol.

Preferred alumina in accord with this invention is boehmite powders having a diameter of less than about 100 microns, and preferably between from about 5 microns to 50 microns. The alumina can be dissolved in a variety of solvents including water or alcohol. An especially preferred alumina is boehmite and particularly boehmite P3 powder.

Evidence of the direct bonding of vinyl silanes to polycarbonate through the vinyl groups was determined using X-Ray Photoelectron Spectroscopy (XPS). Experiments were designed and performed to determine the composition of pretreated polycarbonate surfaces and their interaction with silane primers. The binding properties were highly dependent upon the conditions that the polycarbonate surfaces were prepared and the primers were applied.

XPS experiments were performed to address three primary issues in our efforts to improve the reliability and consistency of our coatings. For these experiments Polycarbonate substrates were corona treated under controlled conditions:

(1) PC substrates were corona treated under dry conditions in a Plexiglas glove box purged at a high flow rate with anhydrous air (RH < 17%) (2) PC substrates were corona treated under wet conditions inside the same glove box in the presence of an open dish of a saturated aqueous NaHSO4 (a salt solution that provides a 50% and purge gas for the box was sparged through the same saturated salt solution. (RH = 34%) (3) VTES and other Primers were applied and rinsed under the same conditions that the Substrates were pretreated to investigate the role of humidity in primer binding.

These PC surface studies gave additional information about: (1) the surface composition of PC corona treated under different environmental conditions (2) the basic binding properties of silane primers to PC surfaces pretreated under various condition, and (3) mechanism of silane primer interaction with these surfaces. The high resolution C,H,N scans looked at the individual binding energies of these specific atoms to provide more detailed information about the surface species for these atoms (e.g. the relative populations of C-O v. C=O v.O=CO for carbon). In this study, experimental conditions were controlled and differentiated. Active dessicants (Drierite Salts) were placed in the box for an extended time (~7days) preceding the experiments to more effectively remove adsorbed water from the box surfaces and equipment to reduce and better control. These experiments provided a more consistent and reproducible wet conditions and provide similar levels of oxides of nitrogen (NOχ) formed corona. These altered conditions provided dry conditions of 17% RH and 69°F and wet conditions of 34% RH, 68°F.

Treatment of the surface with mono-functional silane probes will help to establish the nature of the interaction and verify our current Si-OR C-OH picture. The use of trimethylmethoxysilane (TMMeOS) and frimethylvinylsilane (TMVS) establishes the effectiveness of the interaction of the organic and alkoxy portions of the VTES primer with the treated PC surface.

Samples were prepared in three series to look at a variety of basic issues. Series A was prepared to establish the nature of the PC after corona treatment under wet conditions and to establish the binding properties of the VTES primer and Si-OR groups to these surfaces. Series B was prepared to establish the nature of the PC after corona treatment under dry conditions and to establish the binding properties of the VTES primer to these surfaces. Series C was prepared to establish the nature of the PC after corona treatment under dry conditions and to establish the binding properties of the Si-OR and Si-CH=CH2 groups to these surfaces.

Series A- Wet Corona, Wet Corona + Rinse, Wet Corona + Primer + Rinse, Wet Corona + TMMeOS + Rinse Series B- Dry Corona, Dry Corona + Rinse, Dry Corona + Primer + Rinse

Series C- Dry Corona + TMMeOS Pr + 2 Rinse; Dry Corona + TMMeOS Pr +10 Rinse; Dry Corona + TMViS Pr + 2 Rinse;

Corona treatment of injection-molded polycarbonate in high humidity (RH >33%) produces a higher level of oxidized species compared to the first set of drytreated samples (Sample 1 v. Sample 5- Oxygen Content)

The oxidized species are characterized by a relatively low ratio of C=0 to C-O bonds. VTES and other alkoxy containing probe TMMeOS adhere to this surface The oxidized species probably through at least one of the alkoxysilanes reacting/interacting with surface O-(H) sites (Samples 3A & 4A). Corona treatment of injection-molded polycarbonate in low humidity (RH < 17%) produces a very limited number of oxidized species (similar oxygen level to PC w/out Corona treatment) and that surface does adhere Vinyl containing groups(Samples 7B &10C- High Si Levels)

The oxidized species display a lower ratio of C=0 to C-0 bonds than was observed for the low-humidity samples of 1^st trials (from high Resolution C) The concentration of O-H is low and provides essentially no interaction Si-OH or Si- OR species- TMMeOS fails to adhere

The binding of VTES and TMVS occurs through the vinyl group (Samples 7B &10C)

Bonding is probably through the vinyl groups- the lower water levels yield stable radicals or radical reaction products capable of reacting with the vinyl groups Corona treatment under humid conditions generates oxidized species associated with low molecular weight surface species from polymer degradation in that they appear to be largely rinsed away in IPA Rinses (Sample 2A Decreased O Levels) Samples Corona treated in Low humidity have a small amount of these low weight species as indicated by similar Oxygen levels with rinsing (Samples 6B and 9C) Although the relative humidity of the 'dry' experiments was relatively high (17% v a more ideal humidity of ~10% RH), the overall oxidation levels and the apparent effects of water were much lower under slightly more humid conditions. This reduction is sufficient to significantly influence the nature of the treated surfaces. This is evidence that under properly controlled conditions, covalent links can be formed between corona treated polycarbonate (and other plastic) substrates, and a protective hardcoating via a silane primer.

A preferred first alkoxysilane for inclusion in the hard coat includes at least one and usually one epoxide group. Illustrative of such alkoxysilanes include: Y- glycidoxypropyltrimethoxysilane, Y-glycidoxypropylfriethoxysilane,Y- glycidoxypropyl(methyl)dimethoxysilane,Y-glycidoxypropyldiethoxysilane and the like. Additionally suitable first alkoxysilanes have been disclosed in the US Pat. No. 5,015,523; the disclosure of which is hereby incorporated by reference.

A variety of second alkoxysilanes are compatible with this invention including methyltriethoxysilane, propyltriethoxysilane, propylfrimethoxysilane, (methyl)dimethoxysilane, propyldiethoxysilane and the like.

As discussed, preferred compatibilizing agents according to the invention help provide for good contact between the hard coat and the substrate to be coated. In preferred invention embodiments, such agents include at least one chemically reactive group which facilitates and participates in covalent bonding (radical co- polymerization). Illustrative of such compatibilizing agents include oxysilanes with a carbon bond conducive to radical co-polymerization such as a vinyl group. Examples of such oxysilanes include vinyltrietehoxysilane, vinyltrimethyloxysilane, vinyl(methyl)dimethoxysilane, vinylpropyldiethoxysilane and the like.

As also discussed the hard coat of this invention can be made and applied to the surface to be coated by one or a combination of different steps. In one embodiment, the hard coat bath may contain up to about 30% solids and include an alcoholic solvent, organometallic solutes, and nanoparticles of alumina or hydrated forms of alumina. If desired, the surfaces of the particles can be functionalized to help prevent agglomeration. In preferred embodiments of the invention, such particles serve not only as the hardening reinforcement but also help catalyze the epoxy precursor materials.

In a more specific example, the application process begins by exposing the surface of the desired substrate to corona discharge, thereby creating a relatively high concentration of free radicals. Without wishing to be bound to any theory, it is believed that the free radicals serve as good bonding sites for a vinyl-based primer which, in turn, provides bonding sites for the actual hard coat. In this example, the primer is applied at about room temperature (25°C) using either conventional dip coating or spin coating methodology. The thickness of the primer is between about 0.1 micron to about 0.5 micron.

Methods for making and applying a corona discharge are known in the field and generally involve standard implementations and procedures.

Particular methods for applying the substrate coatings of this invention are known in the field and include dipping, spinning, spraying and flow coating methods. See e.g., the U.S. Pat. No. 5,015,523.

In embodiments where dip coating is preferred, dipping is generally for about one minute and the cure is for about an hour or less. When fully cured, the epoxy is cross-linked and is covalently bonded to the alumina reinforcement, thereby providing a coating that is both hard and also tough. The substrates are preferably pre-treated and coated with vinyltriethoxysilane. Preferred thickness of the cured coating is between about 3 microns to about 5 microns although that range may be greater or less depending on intended use. A particular method of making the substrate coating is provided in the Drawings.

Referring to Figures 1, 2 and 3, a plastic substrate 12 is first cleaned and a compatibilizing coating 14 is applied to surface. Preferably the compatibilizing coating 14 is applied to all of the surfaces. Alternatively, the compatibilizing coating may be applied to one or more surfaces.

As shown in Figure 2, the compatibilizing coating 14 is further coated with a copolymer filled with about 15% to 35% of a dispersed fine alumina or hydrated forms of alumina powder. For example, the aluminum powder may be about 50 nanometers in size.

Figure 3 shows the abrasion resistant and scratch resistant coating 18, which is produced by completing the cure and cross-polymerization of the components of layers 14 and 16. Layer 14 is primarily a monomolecular layer, and the resultant coating 18 has from about 15% to 35% of the dispersed finely divided alumina in the tough polyoxysilane matrix.

Figure 4 shows steps of the process. A large glass or glass-lined tank 20 is filled with water, and sufficient concentrated hydrochloric acid is added to produce a 0.1 weak acid solution.

The dilute hydrochloric acid may be added from container 24. Finely divided alumina or hydrated forms of alumina powder is added 22. The powder is added from a premeasured supply until the concentration, which is predetermined, is from about 8% to about 11% by weight of the alumina or hydrated forms of alumina in the weak hydrochloric acid solution. A stir 25 stirs the solution while the powder is being added and for about four hours after the powder is added to completely disperse the powder in the weak acid solution. The hydrochloric acid acts as a dispersement which encourages each particle of powder to repel each other particle. Premeasured amounts of y-glycidoxypropyltrimethoxysilane 26 and methyltriethoxysilane 28 are added to the tank 30 in amounts sufficient to achieve about a 5 to 3 molar ratio, respectively, of those components. The mixture is stirred with a mixer 31.

Sufficient hydrochloric acid with dispersed alumina or hydrated forms of alumina is provided in tank 20 so that the mixed components from tank 30 are mixed in a ratio of from about 65% to 85% of the alumina dispersed in the hydrochloric acid to about 35% to 15% of the organic components from tank 30. The entire GPS solution is flowed into tank 36 through valve 32. Then part, for example about half of the hydrochloric acid nano-dispersion, is added to the tank 36 through valve 34, while stir 38 stirs the components for about one half hour until the solution has become homogeneous and stable. The hydrochloric acid acts as a catalyst to polymerize the oxysilanes. A pH of about 4 is retained throughout.

Then the second half of the hydrochloric acid dispersion is added through valve 34 at a slow rate while the mixing by mixer 38 continues. When the entire acid dispersion is added, the mixing is continued for about four hours. Then about 3% to 20% by weight isopropynol is added to the contents of tank 36, and the stirring is continued for one hour.

Meanwhile, the substrates 12 are washed 44 with methanol and wiped dry 46 using clean, non-linting industrial wipes. The surfaces of the substrates 12 are corona-treated 48 for about two to five seconds per square inch. A tank 50 is filled with a 3% to 10% mixture of an oxysilane dissolved in isopropyl alcohol to produce a thin, possibly monomolecular compatibilizing layer by dipping 52 the substrates in tank 50. The subsfrates are rinsed 54 with isopropyl alcohol and air dried 56 for twenty minutes at room temperature, and then dipped in the primary coating solution which is delivered through valve 58 to tank 60. The dipping 52 is followed with a slow withdrawal rate of about 6 to 10 inches per minutes. The coated subsfrates are air dried 66 for about twenty minutes at room temperature, and then are cured in an oven at 120°C for about eight to twelve hours until the epoxy matrix is completely hardened around the dispersed alumina particles.

In a particular embodiment of the method, the substrate coating is made without presence of an alcoholate of zirconium.

In a preferred embodiment of the foregoing method, the alumina or hydrated forms of alumina is boehmite P3 powder having a particle size of about 50 nanometers.

As discussed, the present invention can be used to coat a variety of substrates including synthetic or semi-synthetic substrates. Particular examples include resins, plastics, polymers, and block co-polymers such as those disclosed in co-pending U.S. Pat. Application No. 09/532,448 filed on March 23, 2000 and entitled High Performance Nanocomposites. The disclosure of the U.S.S.N. 09/532,448 application is incorporated herein by reference.

More preferred substrates for use with the invention include polydiethylene glycol bisallyl carbonate resins (known as CR-39™), polycarbonate resins, silicates and borosilicates including glass, copolyester copolymers as well as other synthetic materials. See e.g., the U.S. Pat. No. 5,015,035 and the U.S.S.N. 09/532,448 applications.

As discussed, a particularly preferred subsfrate coating thickness will generally be between about 3 to 5 microns.

Specific tests for evaluating performance of the present subsfrate coatings, as well as test results are disclosed in the Drawings and particularly Figures 5A-C to 8.

As will be appreciated, good and effective adhesion contact can be identified and quantified if desired by one or a combination of recognized tests. Such tests include the following: adhesion include Adhesion in accord with ASTM-3359 (MIL- C-83409, Section 4.2.3.1). Abrasion resistance in accord with ASTM- 1044 (MIL-C- 83409). Haze Gain in accord with ASTM D-1003. Chemical Resistance in accord with ASTM D-543. Humidity Test in accord with Method 507 of MIL-STD-810-E. Thermal Cycling in accord with MIL-C-83409 and Ballistic Impact Test in accord with MIL-V-4351 IC and MIL-STD-662F. Choice of a particular test (or combination thereof) will be guided by intended use of the coated substrate and includes the performance information needed for a particular substrate.

EXAMPLE 1- Preparation of Coating Solution

1. In an appropriate beaker, at room temperature, add the Boehmite P3 Powder to 0.1N HCl to create a 9.1% by weight boehmite concentrated solution. Stir for 4 hours.

2. In a separate beaker, add y-Glycidoxypropyltrimethoxy silane to Methyltriethoxysilane to achieve a 5:3 molar ratio respectively.

Stir for one hour.

3. After the one-hour, weigh out 70%, 75%, or 80% boehmite solution, of the total desired coating solution weight. Add one half of this solution to the GPTMS-MTES solution. Stir for ^lA hour until the solution has become homogeneous and stable.

4. Add the second half of the boehmite solution when Step 3 has been achieved.

5. Stir complete solution for 4 hours.

6. Finally add the desired amount of isopropanol (5%, 10%, or 15%, by weight, of the total coating solution). Stir for one hour.

EXAMPLE 2- Coating of the Polycarbonate Substrate

1. Wash the PC with methanol and wipe dry using a Kimwipe.

2

2. Corona treat the surface for 3 sec/in. .

3. Dip or flow coat the PC with 5% Vinyltriethoxysilane in IPA. Air-dry for 15 minutes at room temperature.

4. Rinse primered surface with IPA. Air-dry for 20 minutes at room temperature.

5. Using a dip coater, dip the substrate in the coating solution with a withdrawal rate of 6-10 in./min. 6. Air dry for 20 minutes at room temperature.

7. Cure at 120°C for 10 hours.

Coating Solution Components:

A. Boehmite dispersion 90.9% 0. IN HCl

9.1 wt% Boehmite particles

B. Monomemer solution y-glycidoxypropyltrimethoxysilane methyltriethoxysilane in 5:3 molar ratio

C. Isopropanol

EXAMPLE 3- Production of Specific Coating Solutions Coating Solutions Components % by weight

A B C

1 70 15 15

2 75 15 10

3 80 15 5

4 70 25 5

5 75 20 5

6 80 15 5

7 70 25 5

8 75 15 10

9 80 5 15

10 60 25 15

11 68 23 9

12 76 19 5

Example 4- Preparation of dispersion of nanoscale inorganic filler particles (Component C)

A metal oxide powder is added to a container containing an aqueous solution 0.1N HCl until the solution contains 9.1% of the oxide by weight. The dispersion process takes place at room temperature and The oxide is added at a rate of ~1.5g/min. The solution is stirred for an additional 4-20 hr following the final addition of the oxide powder.

Example 5- Mixing of the Coating Solution

5.1 Mixture of Components A and B

69 parts of Glycidoxypropyltrimethoxysilane (Component A) and 31 parts of methyltriethoxysilane (Component B) are mixed together in an appropriate container.

The two components are stirred for 15-60 min to insure adequate mixing of the two components before the addition of any of the other components. 5.2 Addition of the Inorganic Filler dispersion to Components A and B

35 parts of 9.1 wt% metal oxide dispersion from Example 5 are added to 15 parts of the silane mixture made in Example 5.1. This mixture is allowed to mix and react for 30 min. This mixture is generally stirred overnight (~12hr) before the addition of solvent.

5.3 Addition of Solvent

15 parts of isopropanol (Component D) are added to the 85 parts of mixture of Components A,B, and C made in Example 5.2. The mixture is stirred for l-4hr following the addition of the solvent.

Example 6- Mixing of Additional Coating Solution

Components C and D can be added to the mixture of silanes made in Example 5.1 in a variety of ratios to make coatings suitable for use in the overall coating system. A number of these additional examples were mixed according to the general procedures outlined in Example 5. These additional Examples are presented in Table 1 , below.

Table 1. Example Coating Formulations

Example 7- Cleaning and Pretreatment of the Polycarbonate Substrate

(1) Cleaning of the Polycarbonate substrate

The polycarbonate substrate is completely wetted w th methanol and then flooded with a generous amount of the solvent. The procedure is repeated until each surface of the polycarbonate surface to be coated is wetted and flooded with methanol at least twice. Following the methanol washings, The polycarbonate substrate is completely wetted with isopropanol and then flooded with a generous amount of the solvent. The procedure is repeated until each surface of the polycarbonate surface to be coated is wetted and flooded with isopropanol at least twice. Following the final isopropanol washing, the substrate is dried for at least 10 min.

(2) Preparation of the Vinyltriethoxysilane (VTES) Primer Solution

100 ml (78.5 g) of anhydrous isopropanol (IPA) are transferred via cannula under nitrogen flow. 4.13 g of Vinyltriethoxysilane (NTES) are weighed out and the anhydrous IPA is rapidly added to the VTES. The storage bottle is purged with nitrogen and the mixture is stirred magnetically for 5 to 30 min. The VTES and IPA reagents are purged with dry nitrogen following use.

(3) Corona Discharge Treatment of the Polycarbonate Polycarbonate Plaques or other articles are treated with corona discharge from a Corotec, Inc. Plasma Jet PJ- limit. Polycarbonate articles are held V≥ inch from the

2 eelleeccttrrooddee dduuririnngg ttrreeaattmmeenntt.. SSuulbsfrates are exposed for approximately 3 sec/in during the corona discharge treatment.

(4) Application of Primer to the Corona Treated Polycarbonate

The polycarbonate is Flow coated with the 5 wt% VTES primer solution from a squirt bottle. The substrate is entirely wetted with the solution. The solvent is dried for a period of 2-3 min to evaporate the solvent and allow intimate contact between the VTES and the substrate. After this initial drying period, the substrate is rinsed two times with anhydrous IPA. These rinsing are to remove the excess and weakly bound VTES from the surface. The substrate is dried 3-4 min to allow complete evaporation of the solvent. The hard coating is applied as soon as possible after this final coating procedure.

Example 8- Coating and Curing of the Coating Formulation on Polycarbonate Substrates

(1) Coating of the Polycarbonate substrate

A polycarbonate substrate pretreated and primed as described in Example 7 is immersed in a coating solution as described in Examples 5 or 6. The substrate is held stationary for approximately 10 seconds and then withdrawn from the formulation bath. The substrate is withdrawn at a rate of approximately 24 inches/min. The entrained film is allowed to air dry for approximately 20-25 min.

(2) Curing of the Coated Polycarbonate substrate The dried film is placed into a convection oven preheated to 120C. The film is cured for lO hr at 120C.

Example 9- Abrasion Resistance Tests

ABRASION-RESISTANCE - Abrasion resistance was evaluated via the Taber test according to ASTM D1044. Triton nanocomposite coatings display an excellent level of abrasion-resistance. The coating characteristics are highlighted in Table 2, below:

Table 2. Taber Abrasion Test Results

Example 10- Adhesion Tests

1. ADHESION TEST - Adhesion was evaluated via a tape adhesion test according to ASTM D 3359. All the coatings display perfect (100%) adhesion in the standard tape test performed on a Crosshatch using 670M Scotch tape.

2. ADHESION (IN BOILING WATER AND STEAM)- Adhesion was evaluated under more extreme conditions by performing the standard tape test (ASTM D 3359) after the exposure to boiling water and steam as described previously. All the coatings display perfect (100%) adhesion in the standard tape test performed on a Crosshatch using 670M Scotch tape.

Example 11- Thermal and Environmental Exposure Tests

THERMAL AND ENVIRONMENTAL EXPOSURE- The long-term stability of the film during environmental exposure was evaluated according to thermal and humidity cycling tests as per MIL STD 810 Method 507.3. All the coatings display perfect adhesion with no evidence of peeling or haze gain after exposure to 91°F to 160°F and 14%-80% humidity (24-hour cycles for a period often days) in a humidity chamber.

Example 12- Chemical Resistance Tests

/. CHEMICAL RESISTANCE TESTS - Chemical resistance was evaluated based on a test similar to ASTM D543. The coatings were exposed to hexane , toluene, methanol, acetone, methylethylketone (MEK), N- methylpyrolidinone (NMP), DEET insect repellent, transmission fluid (Dexron), GBT airline oil, motor oil, and gasoline. After being exposed for 30 min, there was no discoloration, pitting, or loss of adhesion (tested using the standard tape test after the exposures). Example 13- Ballistic Tests

1. BALLISTIC TESTS - Ballistic properties were evaluated as per MIL- STD-662. The coatings showed no sign of crazing or cracking upon repeat (4 shots) ballistic impact with 0.22 caliber fragment simulating projectile at 550 to 560 feet per second (as per MIL-STD-662). Also, the application and curing showed no detrimental effect on the base ballistic properties of the base PC substrate.

Example 14- Flame Resistance Tests

1. FLAME-RESISTANCE TESTS - Cone calorimetry tests were performed on bare Polycarbonate (PC) and coated PC according to ASTM El 354. Table 3, below clearly shows that time to ignition, Total heat released, CO yield and the average heat release rates (HRR) are all improved by coating the PC.

Table 3. Data from the flame-test showing the beneficial effects of nano composite coatings

While the invention has been described with reference to specific embodiments, modifications are variations of the invention may be constructed without departing from the scope of the invention.

All references disclosed herein including patents and other publications are incorporated herein by reference.

Claims

What is claimed is:

1. A coated substrate comprising: a) a substrate, b) a first layer comprising inorganic filler particles dispersed in at least one hydrolyzable silane; and c) a second layer comprising at least one compatibilizing agent in adhesive contact with the substrate.

2. The coated substrate of claim 1, wherein the coated substrate features a haze gain of less than about 5% determined by a standard Taber Abrasion Test.

3. The coated substrate of claim 1, wherein the coated substrate features a negligible loss of adhesion as determined by a standard high temperature adhesion test.

4. The coated substrate of claim 1, wherein the inorganic filler particle is at least one of an oxide, oxohydrate, nitride or carbide of Si, Al, Ti, or Zr.

5. The substrate coating of claim 4, wherein the inorganic filler particles comprise alumina or hydrated forms of alumina, the particles being present in the first layer in an amount of from between about 5% (wt/wt) to 70% (wt/wt).

6. The coated substrate of claim 4, wherein the inorganic filler particles have a diameter of from between about 1 to 200 nanometers.

7. The coated substrate of claim 1 , wherein the hydrolyzable silane comprises a first oxysilane (Component A) having the following formula I:

wherein,

2 i) R is an alkyl group having 1 to 20 carbons, ii) R is an alkyl or epoxy group having 1 to 20 carbons;

4 iii) R is an akyl or alkoxy group having 1 to 20 carbons; and iv) x is 1 or 2, and y is 0 or 1

2 „3 , „4 wwhheerreeiinn the alkyl group of R , R , and R are each the same or different,

8. The coated substrate of claim 7, wherein the epoxy group has the following formula II or III:

-(CH₂)_p-(O-CH₂CH₂)_r-O-CH₂-CH-CH₂

O

II

III

wherein p and q are each independently from 1, 2, 3, 4, 5, or 6, and r is 0, 1, or 2.

9. The coated substrate of claim 7, wherein the first oxysilane (Component A) comprises from between about 5% (wt/wt) to about 85% (wt/wt) of total solids in the first layer.

10. The coated substrate of claim 7, wherein the first oxysilane (Component A) is 3 -glycidoxypropyltrimethoxy silane (GPTMS),

3 -glycidoxypropylfriethoxysilane, 3 -glycidoxypropylmethyldimethoxy silane, 3 -glycidoxypropylmethyldiethoxysilane, 3 ,4-epoxycyclohexyltrimethoxysilane, 3 ,4 epoxycyclohexyltriethoxysilane, 3 ,4-epoxycyclohexylmethyldimethoxysilane, 3,4-epoxycyclohexylmethyldiethoxysilane, 2-glycidoxyethyltrimethoxysilane, glycidoxymethyltrimethoxysilane, epoxypropyltrimethoxysilane, or epoxybutyltrimethoxy silane .

11. The coated substrate of claim 10, wherein the first oxysilane is glycidoxypropyl- or 3,4 epoxycyclohexyltrialkoxysilane.

12. The coated substrate of claim 7, wherein the hydrolyzable silane further comprises a second oxysilane (Component B) having the following formula IV:

IV wherein,

2 i) R is an alkyl group or unsaturated hydrocarbon having 1 to 20 carbons, ii) RR iiss aallkk>yl or an alkoxy group 1 to 20 carbons; and iii) x is 1 or 2,

2 5 wherein the alkyl group of each of R and R is the same or different.

13. The coated substrate of claim 12, wherein the second oxysilane (Component B) comprises from between about 5% (wt/wt) to about 85% (wt/wt) of total solids in the first layer.

14. The coated substrate of claim 12, wherein the second oxysilane is tetraethoxysilane, teframethoxysilane, tefrapropoxysilane, tetraisopropylsilane tefrabutoxysilane, methyltriethoxysilane, methylfrimethoxysilane, methyltriproxysilane, , methyltriisopropylsilane methyltributoxysilane, ethyltriethoxysilane, ethyltrimethoxysilane, ethyltriproxysilane, ethyltriisopropylsilane, ethyltributoxysilane, propyltriethoxysilane, propyltrimethoxysilane, phenyltriethoxysilane, phenyltrimethoxysilane, octyltriethoxysilane, octyltrimethoxysilane, dimethyldiethoxysilane, dimethyldimethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, allyltriethoxysilane, allyltrimethoxysilane, 3 -aminopropy ltriethoxy silane, 3 -aminopropy ltrimethoxy silane, 3 -methacryloxypropy ltriethoxy silane, 3-methacryloxypropyltrimethoxysilane, 3-acryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3 -chloropropy ltrimethoxy silane, 3-cyanopropyltriethoxysilane, or 3 -cyanopropy ltrimethoxy silane .

15. The coated substrate of claim 14, wherein the second oxysilane is tetraethoxysilane, methylfrimethoxysilane, or methyltriethoxysilane .

16. The substrate coating of claim 1 , wherein the hydrolyzable silane is present in the first layer in an amount less than about 20% by weight.

17. The coated substrate of claim 1, wherein the compatibilizing agent comprises a third oxysilane (primer) having the following formula V:

wherein, i) R is a group having 1 to 20 carbons, the group being in the adhesive contact with the substrate,

2 2 ii) RR iiss aann aallkkyyll group having from 1 to 20 carbons; and iii) x is 1, 2, or 3.

18. The coated substrate of claim 17, wherein the adhesive contact comprises a covalent bond between the R group of the third oxysilane (primer) and the substrate.

19. The coated substrate of claim 17, wherein the R group of the third oxysilane (primer) is an unsaturated hydrocarbon, mercapto, cyano, isocyano, amino, imino, hydroxyl, acryloxy, or methacryloxy group.

20. The coated substrate of claim 19, wherein the unsaturated hydrocarbon comprises a vinyl, styryl, or allyl group.

21. The coated substrate of claim 20, wherein the third oxysilane (primer) is vinyltriethoxysilane, vinyltrimethoxysilane, vinyl(methyl)dimethoxysilane, vinylpropyldiethoxysilane.

22. The coated substrate of claim 19, wherein the third oxysilane (primer) is a 3-chlorpropyl trialkoxysilane or a 3-mercaptopropyl trialkoxysilane.

23. The coated substrate of claim 17, wherein the R group of the third oxysilane (primer) comprises an epoxy group having the following formula II or III:

-(CH₂)_p-(O-CH₂CH₂)_r-O-CH₂-CH-CH₂

O

I

II

wherein each of p and q is independently 1, 2, 3, 4, 5, or 6 and r is 0, 1, or 2.

24. The coated subsfrate of claim 23, wherein the third oxysilane (primer) is a glycidoxypropyl- or 3,4 epoxy cyclohexyl-trialkoxy silane.

25. The coated substrate of claim 1, wherein the substrate further comprises at least one solvent for dispersing the inorganic filler particles in the hydrolyzable silane.

26. The coated substrate of claim 1, wherein the first layer is adjacent to the second layer.

27. The coated substrate of claim 1, wherein the second layer has a thickness of between from about 0.1 micron to about 20 microns.

28. The coated substrate of claim 27, wherein the substrate is covalently bonded to at least the second layer.

29. The coated substrate of claim 28, wherein the substrate is covalently bonded to the first and second layers.

30. The coated subsfrate of claim 17, wherein the compatibilizing agent is applied to the substrate as a solution having between from about 100% (wt/wt) to 0.05% (wt/wt) of the third oxysilane (primer).

31. The coated substrate of claim 1 , wherein the substrate was exposed to conditions sufficient to provide the adhesive contact between the substrate and at least one of the first and second layers.

32. The coated subsfrate of claim 31 , wherein the conditions comprise exposing the substrate to at least one of an electrical current, or a reactive solution.

33. The coated substrate of claim 32, wherein the electrical current is a corona or plasma discharge.

35. The coated substrate of claim 32, wherein the reactive solution has a pH below about 2 or above about 13.

36. A coating composition comprising: a) a first layer comprising inorganic filler particles dispersed in at least one hydrolyzable silane; and b) a second layer comprising at least one compatiblizing agent in adhesive contact with a substrate.

37. The coating composition of claim 36, wherein the composition provides the substrate with a haze gain of less than about 5% as determined by a Taber abrasion test.

38. The coating composition of claim 37, wherein the composition provides the substrate with a negligible loss of adhesion as determined by a standard high temperature adhesion test.

39. A coated polydiethyleneglycol bisallyl carbonate (CR-39™) substrate comprising at least one compatibilizing agent in adhesive contact therewith and having at least one of: i) a haze gain of less than about 5% as determined by a Taber abrasion test and ii) a negligible loss of adhesion as determined by a standard high temperature adhesion test.

40. The coated subsfrate of claim 39, wherein the coated subsfrate is covalently bound to the compatibilizing agent.

41. The coated substrate of claim 1 , wherein the substrate comprises or consists of at least one of glass, plastic, resin, polymer, block co-polymer, polymer alloy and graft co-polymer.

42. The coated substrate of claim 41 , wherein the resin is polydiethylene glycol bisallyl carbonate (CR-39™) resin, polycarbonate resin, polymethyl methacrylate resin, polystryene resin, diallylphthalate resin, or a resin formed by radical co-polymerization of co-monomers.

43. An article of manufacture comprising or consisting of the coated substrate of claim 1.

44. The article of manufacture of claim 43, wherein the article is an optical implementation and the substrate comprises or consists of a synthetic resin.

45. The article of manufacture of claim 44, wherein the optical implementation is a lens and the substrate comprises or consists of polydiethylene glycol bisallyl carbonate (CR-39™).

46. A method for coating a substrate comprising: a) exposing the substrate to conditions providing for adhesive contact between the subsfrate and an oxysilane, b) contacting the substrate with at least one compatibilizing agent to form a primed substrate, c) contacting the primed subsfrate with inorganic filler particles dispersed in at least one hydrolyzable silane to coat the primed subsfrate; and d) curing the coated primed subsfrate to form the coated substrate.

47. The method of claim 46, the method further comprising cleaning the substrate.

48. The method of claim 47, wherein the cleaning step is performed before step a) in the method.

49. The method of claim 46, wherein the conditions providing for the adhesive contact conditions comprise exposing the substrate to at least one of an electrical current or a reactive solution.

50. The method of claim 49, wherein the electrical current is a corona or plasma discharge.

51. The method of claim 50, wherein the substrate is exposed to the corona discharge for about 1 to 10 seconds per square inch of the substrate.

52. The method of claim 46, wherein the compatibilizing agent is applied to the subsfrate as solution comprising from between about 0.05% to about 50% compatibilzing agent.

53. The method of claim 46, wherein the inorganic filler particles are at least one of an oxide, oxohydrate, nitride or carbide of Si, Al, Ti, or Zr.

54. The method of claim 53, wherein the particles are alumina or hydrated forms of alumina and before step c) the particles are dispersed in an amount of acid sufficient to form a solution with less than about 90% alumina or hydrated forms of alumina by weight and less than about 40% oxysilanes by weight.

55. The method of claim 54, wherein the solution is diluted with less than about 30% by weight of an alcohol before contacting the primed subsfrate.

56. A kit for performing the methods of claim 46.

57. The coated substrate of claim 1, wherein the coated substrate features good chemical resistance as determined by a standard chemical resistance test.

58. The coated substrate of claim 57, wherein the coated substrate is resistant to at least one of hexane , toluene, methanol, acetone, methylethylketone (MEK), N-methylpyrolidinone (NMP), DEET insect repellent, transmission fluid (Dexron), GBT airline oil, motor oil, and gasoline.